MATMAX,
I'm just trying to get my head around your post.
So, the APU is u/s. The ASU is on standby at the gate. As the engines shutdown on stand, one of them has a jetpipe fire.
The ground staff all rush in and connect the ASU..........
My experience of ground staff is they will be doing Billy big steps in the opposite direction from the aircraft as soon as they see a hint of smoke, never mind a fire. (I did).
Or have I got this wrong?
Is the ASU connected before engine shutdown?
Just asking.
